I've had 6 knee surgeries, including two pretty serious osteotomies. Short term, the tonsillectomy was worse. I went from ~155lbs down to less than 130 in a couple weeks. Keep an eye out for clots. I was a "rare" case and coughed one up about a week post op. This opened the flood gates and after several attempts to cauterize while I was awake, they ended up doing another surgery to get the bleeding stopped. You can imagine how fun it is having a cautery tool shoved down your throat while puking blood.
Not trying to scare you, but it sucked. I very rarely get sick now, so that's good I guess.